Introduction:
Using circulating molecular biomarkers to screen for cancer and other debilitating disorders in a high-throughput and low-cost fashion is becoming increasingly attractive in medicine. One major limitation of investigating protein biomarkers in plasma is that antigenic cancer protein are often invisible through routine plasma proteomics. In contrast, Human Leukocyte Antigen (HLA) presents peptides from the entire proteome on the cell surface. While peptide-HLA complexes are predominantly membrane-bound, a fraction of HLA molecules is released into body fluids which is referred to as soluble HLAs (sHLAs). Recent developments in mass spectrometry (MS)-based proteomics have enabled the acquisition of ever smaller input amounts and therefore enabling valuable information to be extracted out of the peptidome of these circulating sHLA.
Methods:
Plasma from healthy donors were collected and subjected through various sample development methods, from the sample preparation side to the mass spectrometry acquisition methods, via incorporation of recent immunopeptidomics approaches. Once method optimisation is completed, the final method would then be applied to 92 plasma samples of rare cancer patients undergoing immune check point inhibitor therapy to investigate whether there are shared immunopeptidomic profiles among them that would predict patient response to the therapy. In this poster presentation I would only highlight the results from method optimisation.
Preliminary Data:
To ensure reproducibility, we sought to optimize a semi-automated sample preparation based on a modified SAPrIm method on these plasma samples which minimize manual handling time. Improvement in sample preparation and mass spectrometry workflow has allowed for deeper plasma immunopeptidomics coverage without sacrificing the purity of the immunopeptidome in plasma from healthy donor.